The rolling bearing cage is provided for holding the rolling bodies in the form of rollers, that is to say in particular tapered rollers or cylindrical rollers, with a uniform spacing from one another. According to the prior art, corresponding cages may be in the form of an open or closed ring or formed from a multiplicity of segments.
It is known from practice for low cage forces in the case of small rolling bearings to be accommodated substantially without wear by means of plastics cages. In the case of large rolling bearings, the use of injection-molded plastics cages is firstly disadvantageous owing to the high costs for corresponding injection molds, in particular because large rolling bearings are normally also manufactured in relatively low unit quantities. Furthermore, in many cases, plastics cages for large rolling bearings do not exhibit adequate strength. Furthermore, it must be taken into consideration that, in particular in the case of tapered-roller bearings, the cages must also take the form of a section of the shell of a cone, and thus at least cannot readily be manufactured from a flat material.
Within the context of the present invention, it is the intention for the rolling bearing cage to be suitable in particular for large rolling bearings, such that the diameter of the cage is then at least one meter. At this size in particular, although cages can be manufactured inexpensively from simple plastics strips, they exhibit only very low strength in the circumferential direction and are thus not suitable for many applications. Here, it must also be taken into consideration that, specifically in the case of large rolling bearings, retroactive exchange of the bearing is, in part, associated with very high costs and very high outlay. High cage forces can be accommodated by cages composed of steel, wherein steel is sensitive to wear, in particular in the presence of poor lubrication. Additional measures such as nitriding or nitrocarburizing are expensive, as is the use of a high-grade metal with low wear characteristics, such as bronze.
DE 30 41 355 A1 discloses a cage for a conventional ball bearing with an inner raceway, an outer raceway and multiple balls arranged in between, wherein the cage is formed from two sheet-metal parts which each have a coating composed of plastic. The production of a cage of said type formed from two deformed and coated sheet-metal strips is cumbersome and is not suitable for large rolling bearings. Since the coating is initially applied to the punched parts in an electrostatic method or a flow bed method, transitions remain after the connection of the punched parts, at which transitions there can be an increased risk of damage. A thermoplastic, in particular polyamide, is provided as a coating for the purpose of reducing the areas of contact between the cage and the balls and protecting the inner and the outer raceway against wear and reducing the friction coefficient.
DE 197 51 003 A1 discloses a method and a device for coating workpieces with a powdery, granular, liquid or pasty coating medium, wherein the application of the coating medium is performed in a fluidized bed. Excess coating medium is removed before the final melting-on and adhesion to the workpiece. A cumbersome method procedure is thus required. The described method and the described device are provided in particular for endless workpieces which are then subsequently processed into their final shape.
WO 2011/003391 A1 discloses a cage for a rolling bearing, which cage can be manufactured in one piece from a solid material. The cage has deformation regions in order that the rolling bodies can initially be placed into the cage and then fixed after a deformation of the deformation regions. A coating of the cage is not described, and is also not possible because said coating would be destroyed as a result of the deformation of the deformation regions. Retroactive coating is also no longer possible owing to the rolling bodies that are then movably arranged within the cage.
DE 197 31 892 A1 generally describes the coating of an electrically conductive workpiece with a fluidized bed.